Soot blowers employed for cleaning slag from the heat exchanging surfaces of large modern fossil-fueled public utility boilers are in some installations required to be projectable for long distances into boiler spaces. Under severe slagging conditions, it has become increasingly common due to improvements in water cleaning techniques to employ water as the blowing medium, while the boiler is on the line, rather than steam and/or air. A slurry consisting of water with other ingredients has also been employed. In order to be self supporting, the lance tube must be of substantial diameter. The weight of the water in the lance tube and the resultant increased tendency of the tube to sag when projected have limited the length of travel which it has been possible to employ with water blowers as distinguished from steam and air blowers. The object of the present invention is to provide an improved water blower and lance tube construction, particularly for boiler cleaning apparatus of the indicated nature, which is more resistant to undesirable sagging of the lance tube when projected, and which incorporates means which promotes more efficient cooling of the lance tube. Other objects and advantages will become apparent upon consideration of the present disclosure in its entirety.